Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 33
Book Description
Based on column tests conducted between February and June 1997, NERL recommended that in terms of effectiveness in achieving cleanup standards and kinetics, a pyrite-iron combination ranked as the best reactive medium (EPA, 1997). Based on this recommendation, in December 1997 Battelle designed and installed a funnel-and-gate type permeable barrier with two gates. Both gates consist of a reactive cell containing granular iron, preceded by a pre-treatment zone (PTZ). The PTZ in Gate 1 consists of a 1% iron-sand mixture; the PTZ in Gate 2 consists of a 10% pyrite-sand mixture. The aim of the PTZ is to improve the longevity of the reactive medium by scrubbing out oxygen from the groundwater before it reaches the 100% iron zone. In the column tests, EPA also reported potential for pH control when pyrite was used. Dissolved oxygen and high pH are detrimental to the longevity of the reactive medium because these conditions promote the formation of precipitates on the granular iron surfaces, thus potentially altering the reactivity and hydraulic performance of the barrier.